Many heart attacks reported immediately after alcohol consumption has been proved again and even moderate levels of consumption may double the risk of heart attack and stroke within an hour after drinking, a new study has showed.

After analyzing data from 23 studies involving 30,000 participants in the hours and days after drinking alcohol, Elizabeth Mostofsky from Harvard TH Chan School of Public Health in the US said in her paper: “We found that even moderate alcohol consumption – one drink a day for women and up to two drinks a day for men – may raise person’s risk of a heart attack or stroke approximately two-fold within the hour following consumption compared to other times.”

After one day or 24 hours, only heavy alcohol intake has heightened the risk. It means heavy drinking increases risk both in the short-term and the long-term, but drinking smaller amounts has different effects in the subsequent hours than it does in the subsequent days and weeks, she said.

Immediately after alcohol intake, heart rate increases, blood pressure rises and blood platelets become stickier and this may increase the risk of heart attack and stroke, researchers observed.

Howevver, earlier studies have shown that regularly drinking small amounts of alcohol over time appears to lower cardiovascular risk by increasing levels of high-density lipoprotein cholesterol (HDL) or “good” cholesterol, and by reducing the tendency to form blood clots, they noted.

“It is possible that the briefly higher cardiovascular risk in the hours after drinking small amounts of alcohol may be outweighed by the longer term health benefits of regular moderate drinking,” said Mostofsky.

However, heavy alcohol consumption leads to higher risk of heart attack and stroke at all times studied. The researchers warn that six to nine drinks in a day nearly doubled the risk, and 19 to 30 drinks weekly made it riskier by six time more, the researcher said.

The 2015 Dietary Guidelines for Americans prescribed that heavy drinking for men is consuming 15 or more drinks per week and for women it is more than 8 drinks per week. The paper has been published in the American Heart Association’s journal Circulation.